So you've seen the self-parking Lexus and BMW, now check out the LEGO Mindstorms NXT version. There's still a few bugs in the program that need to be worked out, but it gets the job done. Video after the jump. A word from its creator:

It has got an ultrasonic sensor that detects the length of free spaces. Then, when it detects enough space, it makes the necessary movments to park. And when you say "GO!" it returns to the road